Patent GB-731689-A (GB)
Title: Improvements in alarm clocks
IPC: G04B23/04
Filed: 1952-07-17
Abstract: 731,689. Clocks. HAMM, M. A. July 17, 1952 [July 18, 1951; Nov. 7, 1951], No. 18105/52. Class 139. An alarm clock comprises a clock movement, a pair of clock hands driven by the movement, a pair of alarm setting hands concentrically arranged relative to the clock hands, means for releasing the alarm when the clock hands reach the positions of the setting hands and clutches which upon such release, couple each setting hand to its corresponding clock hand and a manually operable member for disengaging said clutches to permit setting of the setting hands. The shaft 5, Figs. 1 and 2, carrying the minute hand 6 and the hollow shaft 14 carrying the hour hand 15 are interconnected by the motion work 24, 25, 22, 21. The minute alarm hand 8 and the hour alarm hand 19 are carried by the hollow shafts 7 and 18 respectively. The shafts 5 and 7 carry the clutch elements 10, 11 and the shafts 14 and 18 the clutch elements 16, 17 respectively. The arrangement is such that axial movement to the left of the shafts 7, 14 causes a finger 13 carried by the element 10 to enter a slot in the element 11 and a pin 20 of the element 16 to enter a hole in the element 17 so that the minute hands 6, 8 and the hour hands 15, 19 rotate together. The hands 8 and 19 are interconnected by a gear train 9, 43, 45, 46. The gear 43 meshes with a gear 42 integral with a disc 41 and carried by a horizontal shaft 35 urged to the left by a spring 26. The shaft 35 carries a bevel gear 40 and a conical collar 36. A U-shaped member 49, 52 urged upwardly by a spring 53 carries a lever 51 which normally locks the hammer 4. A vertical shaft 29 passes through the clock case and carries a knob 27 and a bevel gear 39. To set the alarm hands the knob 27 is depressed whereupon a lever 32 is moved downwardly and a finger 37 thereupon engages the collar 36 to move the shaft 35 to the right against the spring 26. This movement of the shaft 35 is transmitted to the shafts 7, 14 by the disc 41 the rim of which passes between the element 10 and the pinion 9 so that the clutch elements 10, 11 and 16, 17 are disengaged. The bevel gears 39, 40 now intermesh and rotation of the knob 27 is transmitted to the hands 8, 19 by the gear trains 42, 43, 9 and 42, 43, 45, 46 respectively. Depression of the knob 27 also results in the depression of the member 49 against the spring 53 so that the hammer 4 is locked by the lever 51. The member 49 is retained in this alarm locking position by the engagement between the element 10 and the arm 52 of the member 49. The pressure of the spring 53 thus serves to retain the hands 8, 19 in the positions to which they are set. When the minute and hour hands 6 and 15 coincide respectively with the hands 8 and 19, the finger 13 enters the slot in the element 11 and the pin 20 enters the slot in the element 17 under the pressure of the spring 26 thereby coupling the hands 6, 8 and the hands 15, 19 for movement together. When the element 10 is thus moved to the left the member 49, 52 is moved upwardly by the spring 53 and the lever 51 frees the alarm hammer 4. The clutches 10, 11 and 16, 17 need not be co-axial. The alarm spring may be wound by a pawl and ratchet mechanism actuated by depression of a push button the spindle of which may pass through the shaft 29 which is made hollow.